Valence Electrons in Astatine (At)

Valence Electrons in Astatine

Determine the number of valence electrons in Astatine (At, Element 85)

Step 1: Look up the electronic configuration for Astatine

The abbreviated (condensed) ground electronic configuration for Astatine is:

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵

Calculate Electronic Configuration for Astatine

Step 2: Identify the outermost electrons using the electronic configuration

Electrons in atomic orbitals outside the [Xe] core are the outermost electrons:

4f¹⁴ 5d¹⁰ 6s² 6p⁵

Step 3: Use the principle quantum number to identify the valence electrons

Extract the principle quantum number, n, and number of electrons from the electron configuration:

The outermost electrons with the largest principal quantum number (in this case, n = 6) are valence electrons.

Answer

Astatine (At) has 7 (2 + 5) valence electrons.